The present invention relates to a programmed action hypodermic syringe wherein, in one embodiment, the syringe can only be filled by unidirectional plunger motion in a filling direction along the axis (movement in the opposite direction being precluded until the fill stroke is completed) and thereafter, the syringe can only be drained or emptied by unidirectional plunger motion in a draining direction (plunger movement being precluded in a direction opposite to the draining longitudinal direction).
It is desirable to have a hypodermic syringe that can only be filled once and/or drained once after which the syringe is rendered non-reusable and therefore fully disposable. Various devices for this purpose have been proposed. U.S. Pat. No. 4,699,614 to Glazier shows one form of non-reusable syringe. The Glazier syringe includes a hollow, cylindrical, plunger barrel or actuator having a zig-zag Z-shaped channel cut in the interior surface thereof. A plunger is actuated by the plunger barrel by moving a stem with radially protruding pins that cooperate with the channel in the plunger barrel. The plunger itself moves in a syringe barrel. To fill the Glazier syringe, at least one pin moves to a defined position in the Z-shaped channel and when so positioned movement of the plunger barrel with respect to the syringe barrel in an outboard direction causes the plunger, via the then-engaged pin and plunger stem, to fill the syringe barrel. During a subsequent ejection or drain mode, longitudinally inboard movement of the plunger barrel causes abutment of the pin against an opposing side of the Z-shaped channel and causes the pin to move along a channel to another defined pin position in the Z-shaped channel whereupon the pin and plunger engage for movement inboard. Further longitudinal inboard movement of the plunger barrel thus causes the plunger to move towards the closed end of the syringe, draining the syringe barrel. If the plunger barrel is thereafter moved longitudinally outboard, the pin follows a third leg of the Z-shaped channel that opens at the end of the plunger barrel such that when the plunger barrel is retracted after a use, the pin leaves the open end of the Z-shaped channel, the plunger is thereby disengaged, remaining in the fully drained position in the syringe barrel, and the syringe becomes inoperable.
The Glazier is limited to one filling and discharging cycle only if the fill and discharge strokes exceed the length of the Z-shaped channel. The syringe can be re-used an indefinite number of times if the stroke is kept shorter than the channel thereby avoiding release of the pin. If the channel length is any substantial portion of a full stroke, the syringe is not strictly non-reusable as a practical matter, but is only reusable in short strokes. It may also be possible to defeat the device by exerting excessive force.
The Glazier device depends on relative motion between the barrel, which is manually operated by the user, and the plunger seal assembly, to which the pin is fixed. Therefore the user perceives a lost motion when the plunger moves but the plunger seal does not move. This lost motion detracts from the precision of operation as perceived by the user.
U.S. Pat. No. 4,493,703 to Butterfield discloses a hypodermic syringe cartridge with a non-retractable drive piston. The piston includes at least two circumferential grooves in its exterior and the syringe barrel has a plurality of radially inward protruding stop edges that prohibit the withdrawal of the plunger when the stop edges lock in the circumferential channels. A number of such ratchet-like structures have been proposed. Typically, the ratchet structures prevent retraction of the plunger per se, and thus interfere with a syringe filling operation involving retraction.
U.S. Pat. No. 4,391,272 to Staempfli discloses a disposable syringe having similar locking characteristics as described with respect to Butterfield. U.S. Pat. No. 4,367,738 to Legendre et al. discloses a plunger having a plunger stem with a plurality of legs extending both longitudinally outboard and radially outward of a plunger stem. These legs lock with an interior stop surface in the syringe barrel. U.S. Pat. No. 3,478,937 to Solowey discloses a disposable syringe having a locking mechanism with feet that spring outward from the plunger stem. U.S. Pat. No. 4,233,975 to Yerman discloses a single use syringe having a separate blocking plunger that is actuated when the main syringe plunger is in the completely drained position. U.S. Pat. No. 4,391,273 to Chiquiar-Arias discloses a disposable syringe having a plunger with a circumferential groove and a plunger barrel having a inwardly protruding locking pin. U.S. Pat. No. 4,650,468 to Jennings, Jr., discloses a medical syringe having a circumferential groove on the plunger and a radially protruding annular ring in the syringe barrel. U.S. Pat. No. 4,634,428 to Cuu discloses a cover for a disposable syringe. U.S. Pat. No. 4,687,467 to Cygielski discloses a non-reusable medical syringe that destroys the syringe piston after use. U.S. Pat. No. 4,188,950 to Wardlaw discloses a disposable syringe that includes a dismountable end piece that bends the needle. U.S. Pat. No. 3,998,224 to Chiquiar-Arias discloses a disposable syringe utilizing a circumferential channel on the plunger and an annular ring extending inward to the syringe barrel. U.S. Pat. No. 3,747,812 to Karman, et al. discloses a disposable syringe that destroys the end of the syringe barrel. U.S. Pat. No. 3,667,657 to Chiquiar-Arias and U.S. Pat. No. 3,951,146 to Chiquiar-Arias also discloses a disposable syringe that destroys the end of the syringe barrel after use. U.S. Pat. No. 4,026,287 to Haller discloses a syringe having a plunger body with extending screw threads on its piston face that mate with complementary thread channels in the base of the syringe barrel.